1st I treid to upgrade my weapon whit an weapon optimizer, this works for most weapons but not Taubeam cannon?
2nd Also after weapon optimizer rom has been applied the source particle upgrade cannot be applied?, since it falis.
vica versa also does not work, applying source than weapon rom.. looks like bug since it dit work not to long ago......

As far as I can recall, you've never been able to combine optimizers with other non-device enhancers. That is, you can combine a weapon optimizer with e.g. a Makayev Weapon Enhancer to get +fast +75% (assuming the weapon is made by Makayev of course) but you can't stack an optimizer with a hexagene booster to get +fast +10%.

Optimizers were changed relatively recently to not be able to be applied to high-level weapons; I think the cutoff is level 6?

After using a Weapon optimizer ROM no other updates can be applied to the weapon. Most ROM's work only up to level 6 devices/weapons/shields. Above that you need either cubes (for the Heisenmachines computer) or specialized devices to enhance/upgrade weapons/shields. some of these stack (like hexagene boosters) or can be combined with other enhancers, some can't. It is part of the game to find out what is or isn't possible.